WebLayer: allow client to handle downloads.

As with WebView, the client is responsible for handling download
requests. The Android shell client simply uses Android's
DownloadManager.

Bug: none
Change-Id: I0204a2101f675c35682f0c75cbe34a506c7b5e2c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1862121
Commit-Queue: Evan Stade <estade@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#707177}

weblayer/BUILD.gn

@@ -60,6 +60,7 @@ jumbo_static_library("weblayer_lib") {
     "common/content_client_impl.h",
     "public/browser_controller.h",
     "public/browser_observer.h",
+    "public/download_delegate.h",
     "public/fullscreen_delegate.h",
     "public/main.h",
     "public/navigation.h",
@@ -154,6 +155,8 @@ jumbo_static_library("weblayer_lib") {
       "browser/browser_observer_proxy.h",
       "browser/content_view_render_view.cc",
       "browser/content_view_render_view.h",
+      "browser/download_delegate_proxy.cc",
+      "browser/download_delegate_proxy.h",
       "browser/fullscreen_delegate_proxy.cc",
       "browser/fullscreen_delegate_proxy.h",
       "browser/top_controls_container_view.cc",

weblayer/browser/browser_controller_impl.cc

@@ -13,6 +13,7 @@
 #include "weblayer/browser/navigation_controller_impl.h"
 #include "weblayer/browser/profile_impl.h"
 #include "weblayer/public/browser_observer.h"
+#include "weblayer/public/download_delegate.h"
 #include "weblayer/public/fullscreen_delegate.h"
 
 #if !defined(OS_ANDROID)
@@ -75,6 +76,10 @@ BrowserControllerImpl* BrowserControllerImpl::FromWebContents(
       ->controller;
 }
 
+void BrowserControllerImpl::SetDownloadDelegate(DownloadDelegate* delegate) {
+  download_delegate_ = delegate;
+}
+
 void BrowserControllerImpl::SetFullscreenDelegate(
     FullscreenDelegate* delegate) {
   if (delegate == fullscreen_delegate_)

weblayer/browser/browser_controller_impl.h

@@ -56,10 +56,12 @@ class BrowserControllerImpl : public BrowserController,
       jlong native_top_controls_container_view);
 #endif
 
+  DownloadDelegate* download_delegate() { return download_delegate_; }
   FullscreenDelegate* fullscreen_delegate() { return fullscreen_delegate_; }
 
  private:
-  // BrowserController implementation:
+  // BrowserController:
+  void SetDownloadDelegate(DownloadDelegate* delegate) override;
   void SetFullscreenDelegate(FullscreenDelegate* delegate) override;
   void AddObserver(BrowserObserver* observer) override;
   void RemoveObserver(BrowserObserver* observer) override;
@@ -68,7 +70,7 @@ class BrowserControllerImpl : public BrowserController,
   void AttachToView(views::WebView* web_view) override;
 #endif
 
-  // content::WebContentsDelegate implementation:
+  // content::WebContentsDelegate:
   void LoadingStateChanged(content::WebContents* source,
                            bool to_different_document) override;
   void LoadProgressChanged(content::WebContents* source,
@@ -89,7 +91,7 @@ class BrowserControllerImpl : public BrowserController,
   blink::mojom::DisplayMode GetDisplayMode(
       const content::WebContents* web_contents) override;
 
-  // content::WebContentsObserver implementation:
+  // content::WebContentsObserver:
   void DidFirstVisuallyNonEmptyPaint() override;
   void DidFinishNavigation(
       content::NavigationHandle* navigation_handle) override;
@@ -97,6 +99,7 @@ class BrowserControllerImpl : public BrowserController,
   // Called from closure supplied to delegate to exit fullscreen.
   void OnExitFullscreen();
 
+  DownloadDelegate* download_delegate_ = nullptr;
   FullscreenDelegate* fullscreen_delegate_ = nullptr;
   ProfileImpl* profile_;
   std::unique_ptr<content::WebContents> web_contents_;

weblayer/browser/download_delegate_proxy.cc

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "weblayer/browser/download_delegate_proxy.h"
+
+#include "base/android/jni_string.h"
+#include "url/gurl.h"
+#include "weblayer/browser/browser_controller_impl.h"
+#include "weblayer/browser/java/jni/DownloadDelegateProxy_jni.h"
+
+using base::android::AttachCurrentThread;
+using base::android::ConvertUTF8ToJavaString;
+using base::android::ScopedJavaLocalRef;
+
+namespace weblayer {
+
+DownloadDelegateProxy::DownloadDelegateProxy(
+    JNIEnv* env,
+    jobject obj,
+    BrowserController* browser_controller)
+    : browser_controller_(browser_controller), java_delegate_(env, obj) {
+  browser_controller_->SetDownloadDelegate(this);
+}
+
+DownloadDelegateProxy::~DownloadDelegateProxy() {
+  browser_controller_->SetDownloadDelegate(nullptr);
+}
+
+void DownloadDelegateProxy::DownloadRequested(
+    const GURL& url,
+    const std::string& user_agent,
+    const std::string& content_disposition,
+    const std::string& mime_type,
+    int64_t content_length) {
+  JNIEnv* env = AttachCurrentThread();
+  ScopedJavaLocalRef<jstring> jstring_url(
+      ConvertUTF8ToJavaString(env, url.spec()));
+  ScopedJavaLocalRef<jstring> jstring_user_agent(
+      ConvertUTF8ToJavaString(env, user_agent));
+  ScopedJavaLocalRef<jstring> jstring_content_disposition(
+      ConvertUTF8ToJavaString(env, content_disposition));
+  ScopedJavaLocalRef<jstring> jstring_mime_type(
+      ConvertUTF8ToJavaString(env, mime_type));
+  Java_DownloadDelegateProxy_downloadRequested(
+      env, java_delegate_, jstring_url, jstring_user_agent,
+      jstring_content_disposition, jstring_mime_type, content_length);
+}
+
+static jlong JNI_DownloadDelegateProxy_CreateDownloadDelegateProxy(
+    JNIEnv* env,
+    const base::android::JavaParamRef<jobject>& proxy,
+    jlong browser_controller) {
+  return reinterpret_cast<jlong>(new DownloadDelegateProxy(
+      env, proxy,
+      reinterpret_cast<BrowserControllerImpl*>(browser_controller)));
+}
+
+static void JNI_DownloadDelegateProxy_DeleteDownloadDelegateProxy(JNIEnv* env,
+                                                                  jlong proxy) {
+  delete reinterpret_cast<DownloadDelegateProxy*>(proxy);
+}
+
+}  // namespace weblayer

weblayer/browser/download_delegate_proxy.h

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef WEBLAYER_BROWSER_DOWNLOAD_DELEGATE_PROXY_H_
+#define WEBLAYER_BROWSER_DOWNLOAD_DELEGATE_PROXY_H_
+
+#include <jni.h>
+
+#include "base/android/scoped_java_ref.h"
+#include "base/callback.h"
+#include "base/macros.h"
+#include "weblayer/public/download_delegate.h"
+
+namespace weblayer {
+
+class BrowserController;
+
+// Forwards DownloadDelegate calls to the java-side DownloadDelegateProxy.
+class DownloadDelegateProxy : public DownloadDelegate {
+ public:
+  DownloadDelegateProxy(JNIEnv* env,
+                        jobject obj,
+                        BrowserController* browser_controller);
+  ~DownloadDelegateProxy() override;
+
+  // DownloadDelegate:
+  void DownloadRequested(const GURL& url,
+                         const std::string& user_agent,
+                         const std::string& content_disposition,
+                         const std::string& mime_type,
+                         int64_t content_length) override;
+
+ private:
+  BrowserController* browser_controller_;
+  base::android::ScopedJavaGlobalRef<jobject> java_delegate_;
+
+  DISALLOW_COPY_AND_ASSIGN(DownloadDelegateProxy);
+};
+
+}  // namespace weblayer
+
+#endif  // WEBLAYER_BROWSER_DOWNLOAD_DELEGATE_PROXY_H_

weblayer/browser/java/BUILD.gn

@@ -23,6 +23,7 @@ android_library("java") {
     "org/chromium/weblayer_private/BrowserObserverProxy.java",
     "org/chromium/weblayer_private/ContentView.java",
     "org/chromium/weblayer_private/ContentViewRenderView.java",
+    "org/chromium/weblayer_private/DownloadDelegateProxy.java",
     "org/chromium/weblayer_private/FullscreenDelegateProxy.java",
     "org/chromium/weblayer_private/NavigationControllerImpl.java",
     "org/chromium/weblayer_private/NavigationImpl.java",
@@ -52,6 +53,7 @@ generate_jni("jni") {
     "org/chromium/weblayer_private/BrowserControllerImpl.java",
     "org/chromium/weblayer_private/BrowserObserverProxy.java",
     "org/chromium/weblayer_private/ContentViewRenderView.java",
+    "org/chromium/weblayer_private/DownloadDelegateProxy.java",
     "org/chromium/weblayer_private/FullscreenDelegateProxy.java",
     "org/chromium/weblayer_private/NavigationControllerImpl.java",
     "org/chromium/weblayer_private/NavigationImpl.java",
@@ -80,6 +82,7 @@ android_aidl("aidl") {
     "org/chromium/weblayer_private/aidl/IBrowserFragmentController.aidl",
     "org/chromium/weblayer_private/aidl/IChildProcessService.aidl",
     "org/chromium/weblayer_private/aidl/IClientNavigation.aidl",
+    "org/chromium/weblayer_private/aidl/IDownloadDelegateClient.aidl",
     "org/chromium/weblayer_private/aidl/IFullscreenDelegateClient.aidl",
     "org/chromium/weblayer_private/aidl/INavigation.aidl",
     "org/chromium/weblayer_private/aidl/INavigationController.aidl",

weblayer/browser/java/org/chromium/weblayer_private/BrowserControllerImpl.java

@@ -21,6 +21,7 @@ import org.chromium.ui.base.ActivityWindowAndroid;
 import org.chromium.ui.base.ViewAndroidDelegate;
 import org.chromium.weblayer_private.aidl.IBrowserController;
 import org.chromium.weblayer_private.aidl.IBrowserControllerClient;
+import org.chromium.weblayer_private.aidl.IDownloadDelegateClient;
 import org.chromium.weblayer_private.aidl.IFullscreenDelegateClient;
 import org.chromium.weblayer_private.aidl.INavigationControllerClient;
 import org.chromium.weblayer_private.aidl.IObjectWrapper;
@@ -43,6 +44,7 @@ public final class BrowserControllerImpl extends IBrowserController.Stub {
     private WebContents mWebContents;
     private BrowserObserverProxy mBrowserObserverProxy;
     private NavigationControllerImpl mNavigationController;
+    private DownloadDelegateProxy mDownloadDelegateProxy;
     private FullscreenDelegateProxy mFullscreenDelegateProxy;
 
     private static class InternalAccessDelegateImpl
@@ -129,6 +131,21 @@ public final class BrowserControllerImpl extends IBrowserController.Stub {
         mBrowserObserverProxy = new BrowserObserverProxy(mNativeBrowserController, client);
     }
 
+    @Override
+    public void setDownloadDelegateClient(IDownloadDelegateClient client) {
+        if (client != null) {
+            if (mDownloadDelegateProxy == null) {
+                mDownloadDelegateProxy =
+                        new DownloadDelegateProxy(mNativeBrowserController, client);
+            } else {
+                mDownloadDelegateProxy.setClient(client);
+            }
+        } else if (mDownloadDelegateProxy != null) {
+            mDownloadDelegateProxy.destroy();
+            mDownloadDelegateProxy = null;
+        }
+    }
+
     @Override
     public void setFullscreenDelegateClient(IFullscreenDelegateClient client) {
         if (client != null) {
@@ -153,6 +170,10 @@ public final class BrowserControllerImpl extends IBrowserController.Stub {
             mBrowserObserverProxy.destroy();
             mBrowserObserverProxy = null;
         }
+        if (mDownloadDelegateProxy != null) {
+            mDownloadDelegateProxy.destroy();
+            mDownloadDelegateProxy = null;
+        }
         if (mFullscreenDelegateProxy != null) {
             mFullscreenDelegateProxy.destroy();
             mFullscreenDelegateProxy = null;

weblayer/browser/java/org/chromium/weblayer_private/DownloadDelegateProxy.java

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.weblayer_private;
+
+import android.os.RemoteException;
+
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.base.annotations.NativeMethods;
+import org.chromium.weblayer_private.aidl.APICallException;
+import org.chromium.weblayer_private.aidl.IDownloadDelegateClient;
+
+/**
+ * Owns the c++ DownloadDelegateProxy class, which is responsible for forwarding all
+ * DownloadDelegate delegate calls to this class, which in turn forwards to the
+ * DownloadDelegateClient.
+ */
+@JNINamespace("weblayer")
+public final class DownloadDelegateProxy {
+    private long mNativeDownloadDelegateProxy;
+    private IDownloadDelegateClient mClient;
+
+    DownloadDelegateProxy(long browserController, IDownloadDelegateClient client) {
+        assert client != null;
+        mClient = client;
+        mNativeDownloadDelegateProxy =
+                DownloadDelegateProxyJni.get().createDownloadDelegateProxy(this, browserController);
+    }
+
+    public void setClient(IDownloadDelegateClient client) {
+        assert client != null;
+        mClient = client;
+    }
+
+    public void destroy() {
+        DownloadDelegateProxyJni.get().deleteDownloadDelegateProxy(mNativeDownloadDelegateProxy);
+        mNativeDownloadDelegateProxy = 0;
+    }
+
+    @CalledByNative
+    private void downloadRequested(String url, String userAgent, String contentDisposition,
+            String mimetype, long contentLength) {
+        try {
+            mClient.downloadRequested(url, userAgent, contentDisposition, mimetype, contentLength);
+        } catch (RemoteException e) {
+            throw new APICallException(e);
+        }
+    }
+
+    @NativeMethods
+    interface Natives {
+        long createDownloadDelegateProxy(DownloadDelegateProxy proxy, long browserController);
+        void deleteDownloadDelegateProxy(long proxy);
+    }
+}

weblayer/browser/java/org/chromium/weblayer_private/aidl/IBrowserController.aidl

@@ -14,5 +14,7 @@ interface IBrowserController {
 
   INavigationController createNavigationController(in INavigationControllerClient client) = 1;
 
-  void setFullscreenDelegateClient(in IFullscreenDelegateClient client) = 2;
+  void setDownloadDelegateClient(IDownloadDelegateClient client) = 2;
+
+  void setFullscreenDelegateClient(in IFullscreenDelegateClient client) = 3;
 }

weblayer/browser/java/org/chromium/weblayer_private/aidl/IDownloadDelegateClient.aidl

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.weblayer_private.aidl;
+
+/**
+ * Used to forward download requests to the client.
+ */
+interface IDownloadDelegateClient {
+  void downloadRequested(in String url, in String userAgent, in String contentDisposition, in String mimetype, long contentLength) = 0;
+}

weblayer/browser/profile_impl.cc

@@ -6,7 +6,10 @@
 
 #include "build/build_config.h"
 #include "content/public/browser/browser_context.h"
+#include "content/public/browser/download_manager_delegate.h"
 #include "content/public/browser/resource_context.h"
+#include "weblayer/browser/browser_controller_impl.h"
+#include "weblayer/public/download_delegate.h"
 
 #if defined(OS_ANDROID)
 #include "base/android/jni_string.h"
@@ -26,6 +29,38 @@ class ResourceContextImpl : public content::ResourceContext {
   DISALLOW_COPY_AND_ASSIGN(ResourceContextImpl);
 };
 
+class DownloadManagerDelegateImpl : public content::DownloadManagerDelegate {
+ public:
+  DownloadManagerDelegateImpl() = default;
+  ~DownloadManagerDelegateImpl() override = default;
+
+  bool InterceptDownloadIfApplicable(
+      const GURL& url,
+      const std::string& user_agent,
+      const std::string& content_disposition,
+      const std::string& mime_type,
+      const std::string& request_origin,
+      int64_t content_length,
+      bool is_transient,
+      content::WebContents* web_contents) override {
+    // If there's no DownloadDelegate, the download is simply dropped.
+    auto* browser = BrowserControllerImpl::FromWebContents(web_contents);
+    if (!browser)
+      return true;
+
+    DownloadDelegate* delegate = browser->download_delegate();
+    if (!delegate)
+      return true;
+
+    delegate->DownloadRequested(url, user_agent, content_disposition, mime_type,
+                                content_length);
+    return true;
+  }
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(DownloadManagerDelegateImpl);
+};
+
 }  // namespace
 
 class ProfileImpl::BrowserContextImpl : public content::BrowserContext {
@@ -50,7 +85,7 @@ class ProfileImpl::BrowserContextImpl : public content::BrowserContext {
   bool IsOffTheRecord() override { return path_.empty(); }
 
   content::DownloadManagerDelegate* GetDownloadManagerDelegate() override {
-    return nullptr;
+    return &download_delegate_;
   }
 
   content::ResourceContext* GetResourceContext() override {
@@ -108,6 +143,7 @@ class ProfileImpl::BrowserContextImpl : public content::BrowserContext {
  private:
   base::FilePath path_;
   std::unique_ptr<ResourceContextImpl> resource_context_;
+  DownloadManagerDelegateImpl download_delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserContextImpl);
 };

weblayer/public/browser_controller.h

@@ -17,6 +17,7 @@ class WebView;
 
 namespace weblayer {
 class BrowserObserver;
+class DownloadDelegate;
 class FullscreenDelegate;
 class Profile;
 class NavigationController;
@@ -32,6 +33,9 @@ class BrowserController {
 
   virtual ~BrowserController() {}
 
+  // Sets the DownloadDelegate. If none is set, downloads will be dropped.
+  virtual void SetDownloadDelegate(DownloadDelegate* delegate) = 0;
+
   // Sets the FullscreenDelegate. Setting a non-null value implicitly enables
   // fullscreen.
   virtual void SetFullscreenDelegate(FullscreenDelegate* delegate) = 0;

weblayer/public/download_delegate.h

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef WEBLAYER_PUBLIC_DOWNLOAD_DELEGATE_H_
+#define WEBLAYER_PUBLIC_DOWNLOAD_DELEGATE_H_
+
+#include <string>
+
+class GURL;
+
+namespace weblayer {
+
+// An interface that allows clients to handle download requests originating in
+// the browser.
+class DownloadDelegate {
+ public:
+  // A download of |url| has been requested with the specified details. If
+  // ignored, the download will be dropped.
+  virtual void DownloadRequested(const GURL& url,
+                                 const std::string& user_agent,
+                                 const std::string& content_disposition,
+                                 const std::string& mime_type,
+                                 int64_t content_length) = 0;
+
+ protected:
+  virtual ~DownloadDelegate() {}
+};
+
+}  // namespace weblayer
+
+#endif  // WEBLAYER_PUBLIC_DOWNLOAD_DELEGATE_H_

weblayer/public/java/BUILD.gn

@@ -27,6 +27,7 @@ template("weblayer_java") {
       "org/chromium/weblayer/BrowserFragmentController.java",
       "org/chromium/weblayer/BrowserObserver.java",
       "org/chromium/weblayer/Callback.java",
+      "org/chromium/weblayer/DownloadDelegate.java",
       "org/chromium/weblayer/FullscreenDelegate.java",
       "org/chromium/weblayer/ListenableFuture.java",
       "org/chromium/weblayer/ListenableResult.java",

weblayer/public/java/org/chromium/weblayer/BrowserController.java

@@ -11,6 +11,7 @@ import android.webkit.ValueCallback;
 import org.chromium.weblayer_private.aidl.APICallException;
 import org.chromium.weblayer_private.aidl.IBrowserController;
 import org.chromium.weblayer_private.aidl.IBrowserControllerClient;
+import org.chromium.weblayer_private.aidl.IDownloadDelegateClient;
 import org.chromium.weblayer_private.aidl.IFullscreenDelegateClient;
 import org.chromium.weblayer_private.aidl.IObjectWrapper;
 import org.chromium.weblayer_private.aidl.ObjectWrapper;
@@ -20,6 +21,7 @@ public final class BrowserController {
     private FullscreenDelegateClientImpl mFullscreenDelegateClient;
     private final NavigationController mNavigationController;
     private final ObserverList<BrowserObserver> mObservers;
+    private DownloadDelegateClientImpl mDownloadDelegateClient;
 
     BrowserController(IBrowserController impl) {
         mImpl = impl;
@@ -33,6 +35,20 @@ public final class BrowserController {
         mNavigationController = NavigationController.create(mImpl);
     }
 
+    public void setDownloadDelegate(DownloadDelegate delegate) {
+        try {
+            if (delegate != null) {
+                mDownloadDelegateClient = new DownloadDelegateClientImpl(delegate);
+                mImpl.setDownloadDelegateClient(mDownloadDelegateClient);
+            } else {
+                mDownloadDelegateClient = null;
+                mImpl.setDownloadDelegateClient(null);
+            }
+        } catch (RemoteException e) {
+            throw new APICallException(e);
+        }
+    }
+
     public void setFullscreenDelegate(FullscreenDelegate delegate) {
         try {
             if (delegate != null) {
@@ -46,6 +62,10 @@ public final class BrowserController {
         }
     }
 
+    public DownloadDelegate getDownloadDelegate() {
+        return mDownloadDelegateClient != null ? mDownloadDelegateClient.getDelegate() : null;
+    }
+
     public FullscreenDelegate getFullscreenDelegate() {
         return mFullscreenDelegateClient != null ? mFullscreenDelegateClient.getDelegate() : null;
     }
@@ -95,6 +115,25 @@ public final class BrowserController {
         }
     }
 
+    private final class DownloadDelegateClientImpl extends IDownloadDelegateClient.Stub {
+        private final DownloadDelegate mDelegate;
+
+        DownloadDelegateClientImpl(DownloadDelegate delegate) {
+            mDelegate = delegate;
+        }
+
+        public DownloadDelegate getDelegate() {
+            return mDelegate;
+        }
+
+        @Override
+        public void downloadRequested(String url, String userAgent, String contentDisposition,
+                String mimetype, long contentLength) {
+            mDelegate.downloadRequested(
+                    url, userAgent, contentDisposition, mimetype, contentLength);
+        }
+    }
+
     private final class FullscreenDelegateClientImpl extends IFullscreenDelegateClient.Stub {
         private FullscreenDelegate mDelegate;
 

weblayer/public/java/org/chromium/weblayer/DownloadDelegate.java

+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.weblayer;
+
+/**
+ * An interface that allows clients to handle download requests originating in the browser.
+ */
+public abstract class DownloadDelegate {
+    /**
+     * A download of has been requested with the specified details.
+     *
+     * @param url the target that should be downloaded
+     * @param userAgent the user agent to be used for the download
+     * @param contentDisposition content-disposition http header, if present
+     * @param mimetype the mimetype of the content reported by the server
+     * @param contentLength the file size reported by the server
+     */
+    public abstract void downloadRequested(String url, String userAgent, String contentDisposition,
+            String mimetype, long contentLength);
+}

weblayer/shell/android/shell_apk/src/org/chromium/weblayer/shell/WebLayerShellActivity.java

@@ -4,6 +4,7 @@
 
 package org.chromium.weblayer.shell;
 
+import android.app.DownloadManager;
 import android.content.Intent;
 import android.net.Uri;
 import android.os.Bundle;
@@ -30,6 +31,7 @@ import org.chromium.weblayer.BrowserController;
 import org.chromium.weblayer.BrowserFragment;
 import org.chromium.weblayer.BrowserFragmentController;
 import org.chromium.weblayer.BrowserObserver;
+import org.chromium.weblayer.DownloadDelegate;
 import org.chromium.weblayer.FullscreenDelegate;
 import org.chromium.weblayer.NavigationController;
 import org.chromium.weblayer.Profile;
@@ -196,6 +198,16 @@ public class WebLayerShellActivity extends FragmentActivity {
                 mLoadProgressBar.setProgress((int) Math.round(100 * progress));
             }
         });
+        mBrowserController.setDownloadDelegate(new DownloadDelegate() {
+            @Override
+            public void downloadRequested(String url, String userAgent, String contentDisposition,
+                    String mimetype, long contentLength) {
+                DownloadManager.Request request = new DownloadManager.Request(Uri.parse(url));
+                request.setNotificationVisibility(
+                        DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
+                getSystemService(DownloadManager.class).enqueue(request);
+            }
+        });
     }
 
     private BrowserFragment getOrCreateBrowserFragment(Bundle savedInstanceState) {